I don't remember that I have ever seen 'madExcept / InterceptClassDestroy' in any report before.Is it correct to assume that something went really wrong before?That computer is reporting also often "system"-errors like GDI. So I believe that that system has some serious problems.

The last time we got a set of 10 error messages within of 6 minutes, 4 of them were empty mails. The screenshot of message 9 shows also the madexcept error window. I can see how the user is trying to click with the mouse on the X for closing the window.What happens in that case? Continue application, restart application, close application or something else?

It looks like you have either memory corruption (e.g. buffer overrun), or your program is trying to release a memory block twice. Unfortunately these crashes are hard to debug.

I'd suggest that you try the option "instantly crash on buffer overrun" to see if that raises any red flags. However, the option currently only works for 32bit processes, and it consumes a lot of extra RAM. So there's a chance your program might out of RAM. But with a bit of luck it might work, and point you to a code location causing a buffer overrun.